1. Field of the Invention
The present invention relates to printing systems and, more particularly, to a device for retaining a flexible printing plate on a print cylinder of a printing machine.
2. Description of Related Art
In a printing machine, flexible printing plates are wrapped around the circumference of a printing cylinder. Various devices and techniques have been used to secure the plates to the cylinder.
For example, Kobler, U.S. Pat. No. 4,557,196 discloses an insert strip located in a groove on the printing cylinder for securing a printing plate around the cylinder. The insert strip has an inner guide portion which fits within the groove and a narrower separating wall portion that carries an abutment pin. The abutment pin is received within notches at the ends of the printing plate to maintain the lateral registration of the plate on the cylinder. The insert strip can be irremovably adhered to the groove in the cylinder or can be made axially slidable within the groove to allow for adjustment of the plate.
Gevis, U.S. Pat. No. 5,107,763, which is assigned to the same assignee as the present invention, discloses a resilient locking member which presses a curved tail member of the printing plate against the curved wall of a cavity in the cylinder. A lock rotor is mounted for rotation within the cavity such that when the rotor is rotated from a locked to an unlocked position, the locking member is disengaged from the cavity wall.
Batz, U.S. Pat. No. 5,156,091, discloses an axially adjustable register pin assembly positioned on an insertion bar that is received in the cylinder. The shiftable register pin assembly uses an eccentric adjusted bolt and spaced fastening screws positioned in elongated fastening holes to effect axial shifting of the register pin, which provides for shifting of the printing plate on the cylinder.
Kobler et al., U.S. Pat. No. 5,375,520, discloses a plurality of leaf-shaped springs disposed in a slot of the cylinder to retain the printing plates on the cylinder. The u-shaped springs have two legs which rest in the slot and one leg is elongated and tensions the edges of the printing plates against the wall of the slot.
There remains a need for a device for securely retaining printing plates on a cylinder which allows for easily installation and removal of the plates.